1. Field of the Invention
The present field of the invention is related to a wafer container, and more particularly, to a wafer container using magnet for sealing and lock-fastening the door and the container body.
2. Description of the Prior Art
The semiconductor wafers are transferred to different stations to apply the various processes in the required equipments. A sealed container is provided for automatic transfer to prevent the is pollution from occurring during transferring process. A front opening unified pod (FOUP) according to the conventional prior art includes a container body and a door. The container body is disposed with a plurality of slots for horizontally supporting a plurality of wafers, and an opening is located on a sidewall of the container body for importing and exporting the wafers. The door includes an outer surface and an inner surface and is joined with the opening of the container body via the inner surface to protect the plurality of wafers within the container body. Moreover, two latch components are disposed between the outer surface and the inner surface of the door, the latch component comprising a cam and a pair of sliding devices in connection with the cam. Therefore, when the cam rotates in certain direction, the free end of the pair of sliding devices extends out of the door and fits into the corresponding insertion hole on the container body for the door and the container body to be lock-fastened to each other.
In the aforementioned FOUP, a seal element is disposed near the opening of the container body; therefore, the free end of the sliding devices presses the seal element of the container body while extending out of the door to achieve the effect of air tightness. However, usually the door is disposed with only two cams and two pairs of sliding devices, and thus the seal element is only pressed by the door on four points, which easily causes defective air tightness of the FOUP. Therefore, as shown in FIG. 1, which is a view of a wafer container of the conventional prior art. The inner surface 220 of the door 200 of the wafer container is disposed with a magnet 250, and at the inner edge of the opening 120 of the container body 100 is disposed with a magnetic component 130 to be attracted by the magnet 250, metal piece for example, the outer surface of the aforementioned magnet 250 and of the magnetic component 130 being coated with seal material. Therefore, when the latch device 240 disposed between the inner surface 220 and the outer surface 210 of the door 200 lock-fastens the container body 100, the magnet 250 attracts the magnetic component 130 for the seal material of the inner surface 220 of the door 200 (i.e. seal material coating the magnet 250) and the seal material on the container body 100 (i.e. seal material coating the magnetic component 130) to contact each other to enhance the effect of air tightness.
And as shown in FIG. 2, which is a view of another wafer container of the conventional prior art. At the inner edge of the opening 120 of the container body 100 of this wafer container are disposed with magnet 140 and a plurality of insertion holes 150. The magnet 140 can attract a magnetic component disposed around the inner surface of the first door (not shown in Figure) for the container body 100 to be lock-fastened with the door via magnetic attraction. Moreover, the same container body 100 can also be lock-fastened with a second door (not shown in figure), between the inner surface and the outer surface of the second door being disposed with cam and sliding devices for the sliding devices to fit into the plurality of insertion holes 150 of the container body 100 via the rotation of the cam. Therefore, the container body 100 can be assembled with door lock-fastened in different forms.
In the above-mentioned wafer container, the magnet 250 and the magnetic component 130 are used to enhance the effect of air tightness. However, since the latch device 240 is disposed between the inner surface 220 and the outer surface 210 of the door 200, the thickness of the door 200 is thus larger and the distance between the front side and the back side of the FOUP cannot be effectively shortened. The other discloses the method to lock-fasten the door and the container body with each other via magnetic attraction. However, the magnetic flux of the magnet may leak into the interior of the container body and affect the stability of circuit of wafers in the container body. In addition, with the magnetic attraction force weakened due to the leakage of the magnetic flux, the door and the container body may thus escape from each other easily during the transportation process of wafer container filled with wafers.